SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78315e67820c775550a430bf912fad52bcf38d42a6e500ad51a0d584f1716b38' 
  AND token = 'iFnbyoVGofXCluiNpjH4r7KmY0TtCh+kSduS2H3nqaA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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