SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fbc9e72952a0811b8e2ae019584fba7c2e8703f1053f5fd7e1896f5fb9f51a81' 
  AND token = 'DB8lKokqm9iGx6L/c+YJw9mU5pX4dqNW7gL+sZm3c1w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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