SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c4fbe3ecf93436662298471d762886b6224893bdb41433c2bcd608877cb4a2f' 
  AND token = 'PJRzxsIqX3+YUEWqjDcZsrIy1v2rxOx+vCcdd1mM78s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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