SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '820bbf760bbe5419ddd614cfb90666a31e41ba55dd42e0c0869368864f270ac8' 
  AND token = 'w+PVI9eQUakIDpAhmrA4cz2tN9zGIjM9ils9XVtAEqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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