SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c3c21552043164575c1084ad3df3cf0061c68d4fbf4cab79961211b2e756c98' 
  AND token = 'EJ8YyqiWfzauD0rSvOyDwtkNTZWnWYQ1KQmru7B7f4g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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