SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac0675426017317d6149355115902bef6a71212843d5f836f35e6beb84b95269' 
  AND token = 'NthZzs2PiUa82ujmTxDkFYiFxca8iUV8dBIFagBB87U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00074

JSON explain

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