SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0b8b7c1a746cc6e18f7b89e247ac697e7e021427faf773da0dafb13df25ef80f' 
  AND token = 'mFOz4iTrbsLpqXMul+xHOkhDZ2eBQTjCwsxeY83lt7w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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