SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd80174b9fdc1ae8f183302a27970c13d7eafdf5e3cce8aeefe41f09ad17c5de4' 
  AND token = '5/lZ2iWWOzrc0R+sY3aNLcvobVL1StjtNudUdwtJLBw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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