SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83c9f0c561a3ce3230be6197a78c92f090eb40f9200d8aacc53ca04dba25c105' 
  AND token = 'FhA7Bf+KdMzyGKCy3tV8CIbLkhqZ73ZFtiqyPKCw9ds=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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