SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9c28ca2923586c50b76d8c94b5b52c5c632a52ceeaa357a745655f4bf6abe45' 
  AND token = 'Az/i2xvfLNuLKNKRKE2VmWb6PtjUIDuBBw5pdb3DCro=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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