SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '770ae3b586c1ae75972a2a391922c9463aad449487f19fbbdb668c53835c7d7e' 
  AND token = 'rEOvQDARZjaZqCo+V4p8t5xiLk/1AWfKc9Dbyj36hRs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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