SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'c20a39b73de551395b5b5a064a699f499a823609e73747caea13d3efccc97af8' 
  AND token = 'Emzb0pjVzyHSEfezDUydyC4E1hiqbA8142lAVP8flXo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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