SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7c2058848df313e406c3269874665f5b34f6e93c0e01bdc73e5eb44986c623f' 
  AND token = '9qwhmFGNu5OlACMZfZtnh1ZMgJwES+pOeKy/IszKNwQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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