SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5861a84b761b5a758053660e2d4a9f21490df43b41d65d8b5253a40a3b64810' 
  AND token = 'PzgjdAkpbubYjsMMLjMDXgQFVmGJ/VTUrn8NVCyYrkI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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