SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '347721c08c453110b356f9a843224ad02261f2f80c638e4786c11061d0369539' 
  AND token = '1tGC2Hb3vSAXULPULpXsM1PjdLMH17kfNAXoD/S/SUg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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