SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de1ee573a2af77f7bcc22e3b6e02876683cf446515a29332d6e7cca97e40ce01' 
  AND token = 'K+OZHFalmsbBp0V8BXnMbfrKo2nPPMvjymLetAbWccU=' 
  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"
    }
  }
}