SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '753ecb9c62150f315f6790ca67bc166ce410e430b03d3edc7c063e720a43a421' 
  AND token = 'EmVShe+WpbJaG9e1PpmAn8dPjmTahmQjOC91QxYQgXg=' 
  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"
    }
  }
}