SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57681ccb7cb051ce9842430504777a8df00756027e31ec8eafc04bee12a27a49' 
  AND token = 'YMkcohyR2+DK0kwgs90e3Z1eIn7LVessfqbfFwNi4jI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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