SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd914d1109105182af8763137670256789477bfa272d40560d6e84ac542eb0784' 
  AND token = 'SR6jnBsSaMc07/ZpcVSBuusGhZ6WBzYOnxyjCFjUvxc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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