SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68451b63e2be4ac31c81452eed03f00ed69f1f85462c50e35e6616e6755e8904' 
  AND token = 'HfjYQQzHsIsBGwgDKKn5zuRStmX7KgW+ve5CxudYLKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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