SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb5c8e5e5fb69e5d6dac0b054f422ed760a6df962af04612dd7ff68025642934' 
  AND token = 'HpAd4CqD/M/udtQchfqrSnGzsVR2Oxaz/MpBiOeyGXg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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