SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'a274687b3dece356b600730954f65643e3dc44625d46fe4a76851a40680a08db' 
  AND token = '8jd7OQitWvOH570fm+Z5DQzsk6fdC7e6wCz3rX6EVoI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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