SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8cd31680da3e9f9c58c816e65bbe854933825355437cf4720170387e881f24c1' 
  AND token = 'nq7Q93Nv7Xu/rn9g+iSgp1VoNtaust5RRAYnhy+q2gw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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