SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e6d07acada0170a534ed2d941192b2a0020a3743eb92ea5ee05c74e35eb6c1f' 
  AND token = 'KkQ5ydj+pIgqXwAZpzmV48gNG4F0yw24tLxljYN/6JA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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