SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a62445f09e2951f083da206d6a61ee535192ad20113784eccde24d915bf1ea9b' 
  AND token = 'SCWPnk6YTu+ewHI4XTz8NDk8qMK30qhm95kicOM4fUM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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