SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5a197fde1b4949c4c58836b284c9ee31a2d5f82d7344d3278b4fd4f435148af' 
  AND token = 'FcFAibDmXzU+MqyLxG+oyGsLnRcYyWCNgwDhn7KObA8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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