SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f2da490124137d643a6f51be6c901f3f64805548086a1573592fd711a041aa8' 
  AND token = 'oPR81vfsq/jz2LGoYkZQ7UB72QH4GgDO3+IWaiNai5I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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