SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f9ac42cc5ad9619c56fc7ee2a15a7828ad0de24a587db5535d8d696301be097' 
  AND token = 'C7H6T/vFykL9uFbhPYx/0Qlo0CLG2Xb033gfoZtsMto=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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