SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4295bf8bfa4d16c9a2edfa65be5afbd0d09d7f67cd5e8e457ebcee12bca3dab8' 
  AND token = '38t+s6fpBfpvcqj48mN7Xwu3JHWuo5I2IbrhanC/heo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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