SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b094aacbbfbda5e6c34ebd95c74e9ef9364e46e5047d30c5b0f12ba2b6076c51' 
  AND token = '27sifYQUhhAuCyAwZfAV1NE5qEnR7DZCkLI0PMFlhYY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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