SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e0ade8747a6035b85f91b2f1bcdaccdaf103cfaa92e556a8536159f13c478f15' 
  AND token = 'mXOFUcVChz+EdZnAy0Cnzc2Ohib931Sr/xtjMdKfowc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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