SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0263cead38cdccd25673a93d573ee5fefb187cc1e19c9f6d7360fa1e509eba80' 
  AND token = 'WESQLlDECFbrqlKZNJw3J9836ncv2eFzBgPTWpiZwjs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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