SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'e2121297dd385f6a7f5635bb032d34f9aaaddb3f4f378d1c16879299ae27f812' 
  AND token = 'RVkzpZLKvXxQTDt4WziOvGIFscknkGyVgz/poxfKCjM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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