SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55d26c9ee5bc3bdb1e3b1b8c594a208a37c6f955201919674c8e5a275bdfab32' 
  AND token = '4tCid+jpT1L1S9mR79VqEDaeBlBwHtFZyP0Fssg+v88=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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