SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b0edf08f73e59567b7995be55e27874dadcbfe45cc29ea004b4f3ba189b4a89' 
  AND token = '2pk2PgnT7vSEiWAD1s4+r8tyFmVKFjcsySIdC83iLqA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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