SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1e008388f95919a52fcece0de73a49d572f0d5450325817ac022a29770d937e' 
  AND token = 'pAAxuCxOjIYPqlRg37yNiuF33XZfcKQwMcqyU7y2VGw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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