SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0ff6b1929567c3b9c686f2ff11086c0dda445f8de9a87bf93a27cc9d0aff5f27' 
  AND token = 'jFZk1aBSM2pHKUOWnjAhE5pm500HJ5NfjPXvuXX2Ug4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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