SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f78a5b2288aa707e05f420e3513c43057f04023c0d6ce5566137ee07782557a' 
  AND token = 'UcMh7h9dPBwYTj0RwKnnoEKG6ysYkThF42+caxD66Vc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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