SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd6db80d8d4214af44a685dcc290e376914d6df669a9f2737c3c8a002c7bb8dc' 
  AND token = '+LDKOt3MCVOth51dR/EtpzBPlmoFuXCwUB09hcujsl8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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