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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af6bdf65d0d3dadb1d7e9c8b1a303fcdbcc934617d1382330fac50b4ac07d129' 
  AND token = 'ySPz/jgNqr3BruwIjQ281xfXIgY4uSz6Inp3jR9v76I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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