SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd846ef6b0693c14985738f6e02cfe051f2c28a12af84beb8a98a00c9aebeb9f3' 
  AND token = 'HSH+3eMqfLtAUdxQ7EjBbmUDf41bMzpEbN1mAnkmFXs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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