SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ca61add6dacdf1ad4b63700823129631bc3dbb109990f709f79428a9af653c51' 
  AND token = 'KBYFDusF0HCPagS+M0FuVAKpbADSHBHSwQqiEUykrdk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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