SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74197a3a1508fda7e883389a04529c7ad25668b3512e3fe578f751103ca4df28' 
  AND token = '0Jnn8dMgNrgUkvtB1TndPujpxeWg+bOwwrexD+HFc0E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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