SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38d88b224129cd8bfef2df4b45f805a3850b68caedb474cce9135d185bcf61e1' 
  AND token = 'fCzTnphkxM6mYNiB/9cTDqi9+LdOQjGuhvEw3zZB6RQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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