SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b8a7de56cec5e9776709395f1f14059073790a2b3df7159cbc88500bc3b737b' 
  AND token = '/UPGQ3MKVjkpaIXHAqs4GdgwAk+r4x0bmSBH6KO2vH8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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