SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a155c90d34ac0c0524b443af324511b683bf336261f2c650cee3b646def105c' 
  AND token = 'P7MtlDVycc3vUZ08SdTrDTTdBp3kOkYFhELxcWkLCyw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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