SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '888cb76eaf5b5c22198899b415063df821874378365b673d946e902043941f16' 
  AND token = 'acWui7s9NwAyj0WIOOrPff8TwRKQpCI0uIojfqMZAA8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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