SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55cffaf403453011228b3b6cac2f66ade1bfd8ee82b779e1c20c29ee55c3f5a0' 
  AND token = 'KRPgwl4AR3yu/O/i6PUDV64Q5cEhKPFlzY8CGgHGZlw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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