SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfce6ac7c64c5f9ed65c6606f74f78c6278e5f8cf34bcc420b2da754b5401146' 
  AND token = 'tumsGJAjpur+NVRXOvvJdCBFetC+HriCLCdJCtY6OGs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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