SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '843f8a4a1f1e2f067909d0f1f3539302b7c2c2bb6c5bc767dd25fe4a070d56b9' 
  AND token = 'RcKXZy7xhZ9Sr+VRpHB2mN+xsZG8LxwKZSdS2vtb8zE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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