SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '999e93b451a75ce0c3360fac99b3dc3a97e8fe934dc9616e2ad7949a1e1d305a' 
  AND token = 'Q5HAVUoim2r5LTUHaYrSwx1uQ3DMioo8Twfo0VeFjRc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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