SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20915661b34aceb8fd86bed647d690d9253c75eb723d5c2682a0b42b43005526' 
  AND token = 'u4/huvxAYyL4mmObmKbIS9wyUoHP2r3n8hu1ecVNbq8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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