SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73a690cfe35affeb528b08790d44de9204a3dc5f56807eb9a56b9b1218416794' 
  AND token = 'Rv4BFo7/eQG9htvsdswKrnmkAYdSvma+pywnR4RZDJA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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