SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a90ad8575d84e5f993b200b863610253a2a44825af65703b10c11a30b35e543a' 
  AND token = 'Id/WhKIn+cyPQi+sw3Z5wDaf9aMFjP8mBJHuuoIRSf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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