SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2d23e478ba06661baa942145dbfdf20e5042922ba03029fc4a07bedb6d2558e2' 
  AND token = 'OMGGxDpbNO+HL5NlUINLZ5vbrqKGjF8aQS1hx/3IzUU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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