SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b78990f2e9ad427afcefaec2fc0c4dedcce807bb2dd45c0cec9fee6135e7eeb4' 
  AND token = 'A1dDWohMApnSZVKOraRcGEkgxsxxnSJJWwpcnGdyjbo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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