SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8db4d82219de04cf889a5fddc96e2fc80be400577e521120ecbffd4557762b72' 
  AND token = 'Em5dw4S2jddTpObmpTyeugmC4njuhdPdGYlugiXtCTk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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