SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fa7cdfa2579ddd9d6a2875704ada9f43c640ce4b8ff948ea81e186433761273f' 
  AND token = 'bYq5OLAwweZd3D0XVnnH/SCngfPRfrkyu0AglSRskMk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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