SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '803d95afc922c1a2840e35585c5791de264b1c633351ca0cf20c60bb3231b5cf' 
  AND token = 'znhKhw0r0gkyiCMd4TiErjiU612Xh3fcg5y7NUpON+c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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