SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81a956ea15464730ae9bcdf7495f94fafd3cc89c8ad7624c10aea9a57774f7db' 
  AND token = 'LdB2HGz/C2IYcZqGLGmO1LBglukMFQTdae/DQVtDkq8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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