SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bd663b44c1e9e33ecd6400a159e558a85a5a2666d20c7316d32e747d6a4b6b43' 
  AND token = 'zKULpPBq+K6Lz5/oYdgNJEjUvoyWSG3HJZqE0sjXL+0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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