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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c03bcb7f7a41b2c6f743476308540d37ff0937e5a92cab5c34ba7d957a58f80' 
  AND token = 'sbJ2uOHZMR8Igh+YbHetcLo0fj4bJI2rtNpkBKkV33c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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