SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc891bf3a9a8420342ab2f61ab9f78eab4fba903dda1500088a6e5e12a0cefda' 
  AND token = '+PXQJzGR5lSg/gbHYdctIUnh+vL/ud0XC6qkKSh6aLs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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