SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '135b4c669f460d776a2dfd99f18b63893bf1c5e8ec66c792a5be370f9c326d02' 
  AND token = 'p2GMWSzvuLUVukVIQ/+IaqrphD9v7MXCG1x4zViRBB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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