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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8915b93323d0114dcd463be70dfdab8481b9d4836c9ff1a98e08dc1dcb67fb5' 
  AND token = '6L/S7mSexntDF91CXFv3QWy93DoTqudVpZtIP9N0c50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}