SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff0864336196da4009fb066bce5d2c9150c9e5f58ff0280f84440aad1f651b98' 
  AND token = 'cjmjXRHa0b+vUd4JI4H/unawfyXoePZp2FmwtVlElw0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}