SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b1287b97fdaa9c6650f36d3593615bdcf78e84f36dacafb285c66252bf9b9bb' 
  AND token = 'xIas6plFTu5A4cB5GJwtBEgR38sAxVHDhBdibXjbH8Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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