SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd4825636a50272a1d2f6c390e353a1066465ac0736083cfff76d689050e42527' 
  AND token = 'rxqOTpqUUr4YlCsSy5IIm4L7+xngwiy8GbNamu8hcQo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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