SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8b124b5fb30c2a883f6ff0e0a97f00d95b72d788e0c4ac1afd6c071f97ef3a8' 
  AND token = 'vt4W8IHRSZFDgBWTx/WYHtz6wOBAyvYVo+2OHu7WIHQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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