SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29b3f828c96da3114051316b1ce79d24f1b0d5f1179375e6951a58fe5ed76d40' 
  AND token = 'f4wS7pIOGhEBwnIhMPV9wzYDr9Jmzyth1OJTzOvuc7g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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