SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4e4a711119e6c6190e66515948726d241d2fccd93f58589a80fde9d234a0e2a' 
  AND token = '8EdHykbnqQUfvf/tZ8m745KYb5fxYwedcX71oT1xvV4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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