SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b316cc3e4dcfe0dd5372f13a1ab41b5ba258ea0f2ff471a9a1fe1462882d56dd' 
  AND token = 'jAXKD48XI0DzsgTMa1AuMSz//wA906JlX+9IUXecJb8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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