SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '852eba4d6a1773191f135b7cb922aa618aef003f743605ecb0412de14fe68150' 
  AND token = '9AYgsuIg4sUd7TQta9zmI3t76uQ2HZSFoOHdcweWWe8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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